JPH02265006A - Magneto-resistance effect type thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a high reproducing output by connecting a connecting part to a magneto-resistance effect element of a lead conductor to its element in a part of the outside by a prescribed quantity or above from the part of the magneto-resistance effect element opposed to a yoke, and placing a ferromagnetic film to the outside by a lead conductor connecting part or above of its element. CONSTITUTION:An MR element 2 is formed by 'Permalloy(R)' of thick film, and provided through a suitable insulating layer on the lower side of a clearance between the upper side front yoke 1 and the upper side back yoke 5. An end part in the lateral direction of the MR element 2 is overlapped about 0.5 - 1.5mum to a rear end part of the yoke 1 or a front end part of the yoke 5, and its axis of easy magnetization is set in the longitudinal direction of the MR element 2. On the upper face of both end parts of the MR element 2, a film 3 of a ferromagnetic material of Co - P and Ni - Co, etc. is formed, and this film 3 is formed in an interval position of 5 - 10mum to the outside from both end faces of the yokes 1 and 5. To the upper side of these ferromagnetic films 3, a lead conductor 4 of an Al - Cu film, etc. is joined, and between the MR element 2 and the lower side yoke 7, a bias conductor 6 is provided through a suitable insulating layer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetoresistive thin film magnetic head, and particularly relates to an effect type thin film magnetic head using a magnetic paper t> which is designed to increase reproduction output. be.

[Conventional technology]

A magnetoresistive thin-film magnetic head uses an MR element that is made into a single magnetic domain by a ferromagnetic film and is energized with a sense current, and applies a signal magnetic field generated from a magnetic recording medium to the MR element. It is constructed so that changes in this signal magnetic field can be extracted as voltage changes in the sense current, and can be roughly divided into two types: double-shielded heads (referred to as double-shielded RADs) and yoke-type heads (hereinafter referred to as YMR heads). There is something called. In a double-sided shield type head, the MR element is placed at a position exposed to the sliding surface of the magnetic recording medium of the magnetic head.
In the YMR head, the MR element is arranged at a position away from the magnetic recording medium sliding surface of the magnetic head, and is configured to transmit changes in the signal magnetic field from the magnetic recording medium sliding surface to the MR element using a yoke. Since the MR element of the YMR head is not exposed on the magnetic recording medium sliding surface of the magnetic head, double-sided shielding prevents damage to the MR element due to abrasion of the magnetic recording medium sliding surface and corrosion of the MR element. It is said to be more advantageous than a mold head.

As shown in FIGS. 7 to 9, a conventional YMR head includes an MR element 2 that detects a signal magnetic field generated from a magnetic recording medium 9 as a resistance change, and an MR element 2 that detects a signal magnetic field generated from a magnetic recording medium 9 as a resistance change, and
The upper front yoke 1, upper hack yoke 5, and lower yoke 7 that guide the magnetic flux to the R element 2, the ferromagnetic films 3, 3 that make the MR element 2 into a single domain state, and the width direction of the MR element 2 (direction of arrow Y) ), a bias conductor 6 applies a bias magnetic field to the MR element 2, and a sense current flows in the longitudinal direction of the MR element 2.
A pair of glue conductors 4 are provided for detecting the voltage between both ends of the MR element 2. A magnetic and electrical insulating layer is provided between the upper front yoke 1, the MR element 2, the upper hack yoke 5, the bias conductor 6, and the lower yoke 7, and furthermore, a protective layer (not shown) is provided to protect them. A layer and a protective plate are provided. In addition, the connection portion of the lead conductor 4, 4 with the MR element 2, and the ferromagnetic film 3,
3 is arranged close to both end surfaces of the upper front yoke 1 and the upper hack yoke 5 in order to reduce the longitudinal dimension of the MR element 2 of the YMR head. Furthermore, the direction of the axis of easy magnetization in the MR element 2 is
is set in the longitudinal direction of the MR element 2 when making the MR element 2. In addition, spacing (
gap) 8 is set.

When a sense current is applied to the MR element 2 and the magnetic recording medium 9 is run, a signal magnetic field generated from the magnetic recording medium 9 passes through the upper front yoke 1 and the upper hack yoke 5 to the MR element.
The voltage across the MR element 2 changes in response to changes in the signal magnetic field. Further, by passing a direct current through the bias conductor 6, a desired bias magnetic field is generated and applied to the MR element 2, and the operating point of the MR element 2 is set to a point with good linearity. Furthermore, the MR element 2 and the ferromagnetic film 3
・By ferromagnetic exchange coupling with MR element 3 and applying a weak magnetic field in the longitudinal direction of MR element 2, MR 2 is brought into a single domain state, and the magnetization inside MR element 2 changes discontinuously due to the domain wall movement. This prevents the occurrence of so-called Barkhausen noise.

In addition, in the conventional YMR head, by setting the easy axis of magnetization of the MR element 2 in an inclined direction that is inclined at a predetermined angle with respect to the longitudinal direction of the MR element 2, it is possible to prevent the magnetization caused by the angular dispersion of the easy axis of magnetization of the MR element 2. Some devices are configured to limit the generation area of Barkhausen noise due to switching in magnetization rotation to a magnetic field area outside the operating range.

[Problem to be solved by the invention]

However, as a result of the following experiment, it was found that in the conventional YMR head, the connection portions of the lead conductors 4 and 4 with the MR element 2 and the ferromagnetic films 3 and It was found that because the MR element 2 is placed close to both end surfaces of the upper front yoke 1 and the upper hack yoke 5 so as to make it smaller, the efficiency of detecting the resistance change of the MR element 2 is lowered, and the reproduction output is lowered. .

That is, using a pseudo head consisting of a non-magnetic integrated lower yoke 7, an alternating current magnetic field of - is applied in the width direction of the head tT, MR element 2, and a Kerr effect measuring device with a spot system of about 5 μm is used to measure the magnetic field. The distribution state of the width direction component of the local magnetization of the MR element 2 was measured along the longitudinal direction near the center of the width direction of the MR element 20, and the applied magnetic field Hs at which the magnetization was saturated was determined from the magnetization curve for the applied magnetic field. This applied magnetic field H
The larger S is, the more the magnetic field is fixed, and the smaller S is, the more easily the magnetization of the local portion is rotated by the signal magnetic field, meaning that the sensitivity is high.

The above measurement results are shown in Figure 13, and the sensitivity is extremely high in the range of approximately 5 μm from the ferromagnetic films 3 and 3 (hatched areas in Figures 8 and 9) compared to the intermediate area. It is recognized that the situation is decreasing. Here, as shown in FIG. 10, the width of the MR element 2 is W, the length of the MR element 2 not covered with the ferromagnetic films 3 is I7, and the film thickness of the MR element 2 is t.
, C is the longitudinal length of the region of MR element 2 (magnetization fixed region) where the resistance does not change because the magnetization is fixed, ρ is the specific resistance of MR element 2, and Δρ is the maximum change in the specific resistance ρ of MR element 2.
If so, the extent to which the efficiency of reproduction output will decrease can be estimated as follows.

That is, the resistance R of the MR element part is ■.

If the maximum change resistance ΔR is, Therefore, the resistance change rate ΔR/R is RWT ρ, and when the resistance changes in the entire area of MR clear 2 (C=
Compared to the rate of change in resistance of O), the rate of change in resistance is reduced by a factor of (I, -20)/L. Here, if L-50um and C=5μm as shown in Figure 10, (L-2C)/L
= 0.75, and the efficiency of reproduction output decreases by 25%.

In addition, as the track width becomes narrower due to high-density recording, MR
Although the length L of the element 2 becomes shorter, the length C of the magnetization fixed region hardly changes, so that the reproduction output is further reduced.

The shield type head also has the same problem of low reproduction output efficiency, and as the size of the head decreases, the reproduction output efficiency further decreases.

The present invention has been made in consideration of the above circumstances,
An object of the present invention is to provide a magnetoresistive thin film magnetic head that increases reproduction output.

[Failure to solve the problem]

The magnetoresistive thin film magnetic head of the present invention is an MR head that detects a signal magnetic field generated from a magnetic recording medium as a resistance change.
an element, a yoke that guides magnetic flux from the head gap to the MR element, a ferromagnetic film that puts the MR element in a single domain state, a bias conductor that applies a bias magnetic field in the width direction of the MR element,
A sense current is passed in the longitudinal direction of the M R element, and the M
The present invention is based on a configuration including a pair of lead conductors for extracting voltage changes occurring across the R element, and in order to achieve the above object, the following measures are taken.

However, the connection part of the lead conductor with the MR element is connected to the MR element by a predetermined amount more than the part of the MR element facing the yoke, and the ferromagnetic film is connected to the MR element.
The structure is such that it is disposed outside the lead conductor connection portion of the element.

(Function) In the above configuration, the MR element is placed in a single domain state by the ferromagnetic film, and the operating point is set at a point with good linearity by the bias magnetic field formed by the bias conductor. The magnetic flux of the signal magnetic field generated by the medium is transferred from the head gap to the MR by the yoke.
By guiding the magnetic field to the element, a change in the signal magnetic field is converted into a corresponding change in resistance of the MR element, which is extracted as the mold pressure between both terminals of the MR element. Here, by arranging the ferromagnetic film so that the connecting portion of the lead conductor with the MR element is a predetermined amount or more outside the MR element facing the yoke, the magnetization fixed region of the MR element faces the yoke. It can be set outside the magnetoresistive element, and enables rotation of magnetization in response to changes in the signal magnetic field across the entire part of the magnetoresistive element facing the yoke, increasing the magnetoresistive effect and increasing reproduction output. efficiency can be increased.

In the present invention, the distance between the connection portion of the lead conductor and the magnetoresistive element from the portion of the magnetoresistive element facing the yoke is preferably 5 to 10 μm,
If this distance is smaller than 5 μm, the effect of increasing the reproduction output will be reduced, which is undesirable. If this distance is larger than 10 μm, the length of the head will become too large, which is not preferable.

Further, in the present invention, the lead conductor can be formed to be expanded closer to the end surface side of the yoke than the ferromagnetic film, and can be connected to the region of the magnetoresistive element whose magnetization can be rotated by a signal magnetic field. In this case, MR whose magnetization is fixed between the lead conductors
Since the element area is eliminated, the reproduction output can be further increased.

〔Example〕

1 to 3 show a YMR head according to an embodiment of the present invention.

This YMR head includes a lower yoke 7 made of a high magnetic permeability magnetic material such as a polycrystalline Ni-Zn ferrite substrate, a single crystal or a polycrystalline Mn-Zn ferrite substrate, and an upper front yoke above the lower yoke 7. 1 and a lower hack yoke 5 are provided. The upper front yoke 1 extends rearward from the front end surface 7a of the lower yoke 7, and the upper hack yoke 5 extends further rearward from the upper front yoke 1 at an appropriate interval. The upper front yoke 1 faces the lower yoke 7 at its front end with a head gap 10 in between, and is bent obliquely upward at its rear end.

The front end surface of the upper back yoke 5 is the upper front yoke 1.
They are opposed to each other at an appropriate distance from the rear end surface, and are bent diagonally downward in a step shape at the rear and connected to the lower yoke 7. The upper front yoke 1 and the upper front yoke 5 are, for example, 0. It is made of permalloy with a film thickness of about 5 to 1.0 μm, and constitutes a magnetic flux introduction path that guides the signal magnetic field generated in the magnetic recording medium 9 from the head gap 10 to the MR element 2.

The MR element 2, which detects the signal magnetic field generated from the magnetic recording medium 9 as a resistance change, is formed of permalloy with a film thickness of 200 to 400, for example, and is located below the gap between the upper front yoke 1 and the upper back yoke 50. It is arranged through a suitable insulating layer. The ends of the MR element 2 in the width direction overlap the rear end of the upper front yoke 1 or the front end of the upper back yoke 5 by about 0.5 to 1.5 μm, respectively. Further, the axis of easy magnetization may be set in an inclined direction that is inclined by about 10 to 40 degrees with respect to the longitudinal direction of the MR element 2, but in this case, it is set in the longitudinal direction of the MR element 2.

On the upper surface of both ends of the MR element 2, ferromagnetic films 3 made of a ferromagnetic material such as Co--P, Ni--Co, or N1Co--P having good conductivity and large coercive force are formed. The ferromagnetic films 3 are formed at a distance of 5 to 10 μm outward from both end surfaces of the upper front yoke 1 and the upper hack yoke 5, and have a thickness of 1000 to 2000 μm.

Further, on the upper side of these ferromagnetic films 3, lead conductors 4, made of a thin film having good conductivity such as an AlCu film, etc.
4 are joined.

A bias conductor 6 is disposed between the MR element 2 and the lower yoke 7 via appropriate insulating layers. This bias conductor 6 is made of, for example, an AlCu film, and by passing a direct current through it, a bias magnetic field of desired strength can be applied in the width direction of the MR element 2.

The magnetic recording medium 9 is configured to run in the vertical direction (in the direction of arrow Z) through a position in front of the rad gap 10 across the spacing 8, and the size of the head gap 10 is as follows. Actual minimum recorded wavelength 0.5μm
Corresponding to this, it is set to about 0.2 to 0.3 μm, which is smaller than this.

In the YMR head described above, the region whose magnetization is fixed by the ferromagnetic films 3 is located outside from both end surfaces of the upper front yoke 1 and the upper back yoke 5. In the portion of the MR element 2 facing both end surfaces of the upper front yoke 1 and the upper front yoke 5, the upper front cork 1
The magnetization can be rotated in response to the signal magnetic field transmitted from the head gap 10 via the upper hack yoke 5, and changes in the magnetic field signal can be efficiently converted into resistance changes, and reproduction output can be efficiently obtained. It will be done. As described above, the efficiency of the reproduction output of this YMR head is determined by the 11th
As shown in the figure, when L is estimated as -40μm and C-5μm, ΔR/R=0.8Δρ/ρ, and the reproduction output is low -F! ; J: Approximately 20% +l, so compared to the resistance change rate (0.75Δρ/ρ) in the conventional example, an output increase of (25-20)÷75×100#6% can be obtained.

FIGS. 4 to 6 show YM according to other embodiments of the present invention.
R head is shown.

In this embodiment, the front ends 4a, 4a of the lead 1' conductors 4, 4
is the upper front yoke 1 from the north side of the ferromagnetic 11 film 3.
It is enlarged to both end surfaces of the upper back yoke 5, and a portion of the lead conductors 4 are directly connected to the region of the MR element 2 where magnetization can be rotated in response to the signal (n field). , since the lead conductors 4 and 4 are directly bonded to the region of the MR element 2 where the magnetization can rotate in response to the signal magnetic field, the length of the magnetization fixed region becomes C=O, as shown in FIG. , the resistance value R of the MR element part can be set as R=L/Wt・ρ, and the maximum change resistance ΔR can be set as ΔR=L/Wt・Δρ, which becomes ΔR/R−Δρ/ρ, which is the same as that of conventional YMR. Compared to the head, the output is increased by 25÷75X100°-133%.

Although each of the above embodiments has been described with respect to a YMR head, it goes without saying that the present invention can also be applied to a double-sided shield type head.

(Effects of the Invention) As described above, in the magnetoresistive thin-film magnetic head of the present invention, the connection portion of the lead conductor with the magnetoresistive element is located at a position lower than the portion of the magnetoresistive element that faces the yoke. The ferromagnetic film is connected to the magnetoresistive element at the outer part of the magnetoresistive element, and the ferromagnetic film connects to the lead conductor connection part of the magnetoresistive element (hereafter
Since the MR element is placed outside the ferromagnetic film, the region of the MR element whose magnetization is fixed by the ferromagnetic film is located on the evening side of the region facing the yoke that applies the signal magnetic field of the magnetic recording medium to the MR element from the head gap. As a result, the signal magnetic field generated in the magnetic recording medium can be efficiently detected as a resistance change of the MR element, and a high redistribution force can be obtained.

In particular, in the present invention, the ferromagnetic film is
In the case of installing the MR elements at positions separated by 10 μm, the area of the MR element whose magnetization is fixed by the ferromagnetic film faces the yoke that applies the signal magnetic field of the magnetic recording medium to the MR element from the head gap without increasing the size of the head. The playback output can be increased by positioning it outside the area.

In addition, when the lead conductor is expanded closer to the end surface side of the yoke than the ferromagnetic film and is connected to the region of the magnetoresistive element whose magnetization can be rotated by the signal magnetic field, the magnetization of the M R is fixed.
Since the lead conductor can be connected inside the region of the element, it is possible to achieve effects such as further increasing the reproduction output.

[Brief explanation of drawings]

1 to 3 show a YMR head according to an embodiment of the present invention, in which FIG. 1 is a perspective view, FIG. 2 is a plan view, and FIG. 3 is an A-A in FIG. FIG. FIGS. 4 to 6 show YMR according to other embodiments of the present invention.
4 is a perspective view, FIG. 5 is a plan view, and FIG. 6 is a longitudinal sectional view taken along the line B--B in FIG. 5, showing the head. Figures 7 to 9 show conventional YMR heads, where Figure 7 is a perspective view, Figure 8 is a plan view, and Figure 9 is I) of Figure 8.
-D is a vertical cross-sectional view. FIG. 10 is a schematic diagram showing how to calculate the resistance change rate of a conventional magnetoresistive thin film magnetic head. FIG. 11 is a schematic diagram for calculating the resistance change rate of a YMR head according to an embodiment of the present invention. FIG. 12 is a schematic diagram for calculating the resistance change rate of a YMR head according to another embodiment of the present invention. FIG. 13 is a diagram showing the state of magnetization on the MR element of a conventional magnetoresistive thin film magnetic head. FIG. 1 is an upper front yoke, 2 is an MR element, 3 is a ferromagnetic film, 4 is a lead conductor, 5 is an upper hack yoke, 6 is a bias conductor, 7 is a lower yoke, 9 is a magnetic recording medium, and 10 is a helad gap. be. Patent applicant Sharp Co., Ltd. - J Yen O (○e) Figure 13\7 \~ -8,x/ x-X-X-X-X-X-X-X

Claims (1)

[Claims] 1. A magnetoresistive element that detects a signal magnetic field generated from a magnetic recording medium as a change in resistance, a yoke that guides magnetic flux from a head gap to the magnetoresistive element, and a magnetoresistive element that is in a single domain state. a ferromagnetic film that applies a bias magnetic field in the width direction of the magnetoresistive element, a bias conductor that applies a bias magnetic field in the width direction of the magnetoresistive element, and a sense current that flows in the longitudinal direction of the magnetoresistive element and a voltage change that occurs at both ends of the magnetoresistive element. In a magnetoresistive thin film magnetic head comprising a pair of lead conductors for taking out, the connection portion of the lead conductor with the magnetoresistive element is larger than the portion of the magnetoresistive element facing the yoke by a predetermined amount or more. 1. A magnetoresistive thin film magnetic head connected to a magnetoresistive element at an outer portion thereof, the ferromagnetic film being disposed further outward than a lead conductor connecting portion of the magnetoresistive element. 2. The magnetoresistive thin film magnetic head according to claim 1, wherein the ferromagnetic film is disposed 5 to 10 μm away from a portion of the magnetoresistive element facing the yoke. 3. The magnetoresistive type according to claim 1, wherein the lead conductor is expanded closer to the end surface side of the yoke than the ferromagnetic film and is connected to a region of the magnetoresistive element whose magnetization can be rotated by a signal magnetic field. Thin film magnetic head.